GB2281119A

GB2281119A - Sound moderator

Info

Publication number: GB2281119A
Application number: GB9317062A
Authority: GB
Inventors: Gordon Findlater
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-17
Filing date: 1993-08-17
Publication date: 1995-02-22
Anticipated expiration: 2013-08-17
Also published as: GB2281119B; GB9317062D0

Abstract

There is disclosed an improved sound moderator (silencer) for firearms and or air-guns/rifles, particularly suitable for rim fire 0.22" calibre firearms. Known moderators suffer from a number of problems, such as ease of cleaning, noise minimisation, high number of components, ease of construction, weight, size, and production cost. The present invention provides a sound moderator (5) comprising a body (10) having an internal bore (15) the body being at least partially made from a plastics material such as a polyacetal material. At least part of the internal bore (15) has a helical path provided thereupon (50, 85, 90, 95). Further, the bore (15) is divided into at least two longitudinal chambers (58, 59, 60) by at least one baffle (65,70), the baffle(s) (65, 70) having at least one aperture (75) formed therein and being retained within the bore (15) by helical spring retaining means (85, 90, 95), the retaining means (85, 90, 95) allowing limited longitudinal movement of the baffle(s) (65, 70) about a rest position, in use. <IMAGE>

Description

Sound Moderator This invention relates to an improved sound moderator (silencer) for firearms and or air-guns/rifles, and particularly though not exclusively for rim fire 0.22" calibre firearms.

Sound moderators are known, eg. the Parker Hale

moderator for 0.22" calibre. However, known moderators suffer from a number of problems.

It is an object of the present invention to obviate or mitigate the aforementioned problems in the prior art.

Further objects of at least some embodiments of some aspects of the present invention are to seek to provide a sound moderator which: a. is of a construction which provides ease of cleaning; b. provides internal volume maximisation and, therefore, noise minimisation; c. is constructed of the least number of components possible; d. provides self centring components; e. is of light weight; f. is of small size; g. is cheaper to produce than previously known moderators.

According to a first aspect of the present invention there is provided a sound moderator comprising a body having an internal bore, the body being at least partially made from a plastic material.

Preferably the body may be made from a polyacetal material. Examples of such materials are DELRIN, KEMATAL and CELCON

Use of such plastic materials may provide advantages such as: light weight; corrosion resistance; and attractive colouring of the body.

According to a second aspect of the present invention there is provided a sound moderator comprising a body having an internal bore, at least part of the internal bore having a helical path provided thereupon.

The helical path may be provided by means of a compression spring(s) provided within the internal bore, the outer diameter of the spring(s) being substantially the same size as the diameter of the at least part of the internal bore.

Alternatively, the helical path may be provided by a screw thread(s) formed on the surface of the at least part of the internal bore.

A double helical path may be provided on at least part of the internal bore, the double helical path being provided by a screw thread(s) formed on the surface of the internal bore, and a compression spring(s) provided within the internal bore, the outer diameter of the spring(s) being substantially the same size as the diameter of the internal bore, the screw thread(s) and compression spring(s) spiraling (winding) in opposing directions along the length of the at least part of the internal bore.

The helical path imparts a spiral motion to gas discharged into the moderator from the firearm. It is believed that this assists in reducing the pressure of the gas, thereby reducing the noise emitted.

According to a third aspect of the present invention there is provided a sound moderator comprising a body having an internal bore, the internal bore being divided into at least two longitudinal chambers by at least one baffle, the baffle(s) having at least one aperture formed therein and being retained within the bore by retaining means, the retaining means allowing limited longitudinal movement of the baffle(s) about a rest position, in use.

Preferably the internal bore may be divided into first, second and third longitudinal chambers by first and second baffles.

Preferably the retaining means comprise first, second and third compression springs, a first end of the first spring being in abutting relation to a first lip provided at a first end of the bore, a second end of the first spring being in abutting relation to a first side of the first baffle, a first end of the second spring being in abutting relation to a second side of the first baffle, a second end of the second spring being in abutting relation to a first side of the second baffle, a first end of the third spring being in abutting relation to a second side of the second baffle, and a second end of the third spring being in abutting relation to a second lip provided at a second end of the bore.

Preferably the body comprises a main elongate hollow body and a cap, the main elongate hollow body and cap being threadably connected to each other by co-acting threaded portions on an internal surface of the main body and an external surface of the cap.

Preferably the first chamber is greater in volume than the second chamber.

Preferably the second chamber is greater in volume than the third chamber.

Preferably the first spring is stronger than the second spring.

Preferably also, the second spring is stronger than the third spring.

Preferably the at least one aperture formed in each baffle comprises a central hole.

Preferably also, each baffle may further provide a non-central hole.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, which are: Fig 1 a schematic cross-sectional side view of a sound moderator according to the present invention; Fig 2 a cross-sectional side view of a main elongate body forming part of the moderator of Fig 1; Fig 3 a cross-sectional side view of a cap forming part of the moderator of Fig 1; Fig 4 a side view of a compression spring forming part of the moderator of Fig 1; and Fig 5 a front view of a baffle forming part of the moderator of Fig 1.

Referring to the diagrams, there is provided an embodiment of a sound moderator according to the present invention, generally designated 5, for use with 0.22(4)" calibre. The moderator 5 comprises a cylindrical body 10 having a cylindrical internal bore 15 communicating with an inlet 20 and an outlet 25 provided at first and second ends 30, 35 of the body 10. The inlet is internally threaded to allow attachment to a 0.22" calibre firearm.

The body 10 comprises a main elongate hollow body 40 and a cap 45, the main body 40 and cap 45 being threadably connected by co-acting threaded portions 50, 55 on an internal surface of the main body 40 and an external surface of the cap 45.

The main body 40 and cap 45 are, in this embodiment, made from a poly-acetal material.

In this embodiment the internal bore 15 is divided into first, second and third longitudinal chambers 58, 59, 60 by first and second baffles 65, 70. The first and second chambers 58, 59 may be referred to as primary and secondary expansion chambers respectively. As can be seen from Fig 5, the baffles 65, 70 comprise stainless steel discs approximately 0.040" thick having a first central hole 75 and a second offset hole 80. The baffles 65, 70 are retained within the bore 15 by retaining means in the form of first, second and third compression springs 85, 90, 95.

As can be seen from Figs 1 to 3, a first lip 105 is provided near the first end 30 of the body 10, while a second lip 110 is provided near the second end 35 of the body 10 by an innermost end of the cap 45.

The moderator 5 is constructed by placing, in turn, into the main body 40: the first spring 85, the first baffle 65, the second spring 90, the second baffle 70, and the third spring 95. The cap 45 may then be threadably connected to the main body 40 so as to retain the springs 85, 90, 95 and baffles 65, 70 therein.In this way, a first end of the first spring 85 is held in abutting relation with the first lip 105, a second end of the first spring 85 is held in abutting relation with a first side of the first baffle 65, a first ends of the second spring is held in abutting relation to a second side of the first baffle, a second end of the second spring 90 is held in abutting relation with a first side of the second baffle 70, a first end of the third spring 95 is held in abutting relation with a second side of the second baffle 70, and a second end of the third spring 95 is held in abutting relation with the second lip 110.

In a prefered embodiment the first chamber 58 is greater in volume than the second chamber 59 which is greater in volume than the third chamber 60.

As can also be seen from Fig 1 each spring 85, 90, 95 is a tight fit within the bore 15. The springs 85, 90, 95 therefore provide respective helical paths on the surface of the internal bore. In this embodiment the springs 85, 90, 95 are as follows:- first spring 85: formed from wire having an outer diameter (O.D.) - 0.855", inner diameter (I.D.) = 0.713", length = 1.1875", number of coils = 3; second spring 90: O.D. = 0.855", I.D. = 0.713", length = 1.0625", number of coils = 3.25; third spring 95: O.D. = 0.855", I.D. = 0.735", length = 0.625", number of coils = 2 or 2.5. It is envisaged that the first and second springs 85, 90 along with the first baffle 65 may be replaced by a single spring of O.D. = 0.855", I.D. = 0.713", length = 2.1875", number of coils = 5. The springs are made of stainless steel, in this embodiment.

In use, gas discharged from the firearm into the moderator 5 will enter the internal bore 15 via the inlet 20. The gas will discharge and expand into the first chamber 58. The first spring 85 will cause helical (or swirling) motion to be imparted to the gas, thereby causing disruption thereof. The second and third springs 90, 95 and the offset holes 80 in the baffles 65, 70 contribute similar effects to the discharging gas. These effects cause gas pressure reduction, and therefore cause the emitted noise level to be reduced.

When gas is discharged into the first chamber 58 the first baffle 65 will be caused to move away from the first end of the body 10. Since the baffle 65 is retained in place by the first and second springs 85, 90, the baffle 65 will subsequently return to its original position by a damped oscillatory motion. The second baffle 70 will also act in a similar way when gas is discharged into the second chamber 59.

The embodiment of the present invention hereinbefore described is given by way of example only, and is not meant to limit the scope of the invention in any way.

Claims

1. A sound moderator comprising a body having an internal bore, the body being at least partially made from a plastic material.

2. A sound moderator as claimed in claim 1, wherein the body is made from a polyacetal material.

3. A sound moderator as claimed in claim 2, wherein the polyacetal material is selected from DELRIN, KEMATAL or CELCON CR .T. w'.f)

4. A sound moderator comprising a body having an internal bore, at least part of the internal bore having a helical path provided thereupon.

5. A sound moderator as claimed in claim 4, wherein the helical path is provided by means of a compression spring(s) provided within the internal bore, the outer diameter of the spring(s) being substantially the same size as the diameter of the at least part of the internal bore.

6. A sound moderator as claimed in claim 4, wherein the helical path is provided by a screw thread(s) formed on the surface of the at least part of the internal bore.

7. A sound moderator as claimed in claim 4, wherein a double helical path is provided on at least part of the internal bore, the double helical path being provided by a screw thread(s) formed on the surface of the internal bore, and a compression spring(s) provided within the internal bore, the outer diameter of the spring(s) being substantially the same size as the diameter of the internal bore, the screw thread(s) and compression spring(s) spiraling (winding) in opposing directions along the length of the at least part of the internal bore.

8. A sound moderator comprising a body having an internal bore, the internal bore being divided into at least two longitudinal chambers by at least one baffle, the baffle(s) having at least one aperture formed therein and being retained within the bore by retaining means, the retaining means allowing limited longitudinal movement of the baffle(s) about a rest position, in use.

9. A sound moderator as claimed in claim 8, wherein preferably the internal bore is divided into first, second and third longitudinal chambers by first e and second baffles.

10. A sound moderator as claimed in claim 9, wherein the retaining means comprise first, second and third compression springs, a first end of the first spring being in abutting relation to a first lip provided at a first end of the bore, a second end of the first spring being in abutting relation to a first side of the first baffle, a first end of the second spring being in abutting relation to a second side of the first baffle, a second end of the second spring being in abutting relation to a first side of the second baffle, a first end of the third spring being in abutting relation to a second side of the second baffle, and a second end of the third spring being in abutting relation to a second lip provided at a second end of the bore.

11. A sound moderator as claimed in any preceeding claim, wherein the body comprises a main elongate hollow body and a cap, the main elongate hollow body and cap being threadably connected to each other by co-acting threaded portions on an internal surface of the main body and an external surface of the cap.

12. A sound moderator as claimed in claim 9 or 10, wherein the first chamber is greater in volume than the second chamber.

13. A sound moderator as claimed in claim 9, 10 or 12, wherein preferably the second chamber is greater in volume than the third chamber.

14. A sound moderator as claimed in claim 10, wherein preferably the first spring is stronger than the second spring.

15. A sound moderator as claimed in claims 10 or 14, wherein the second spring is stronger than the third spring.

16. A sound moderator as claimed in claims 8 to 15, wherein preferably the at least one aperture formed in each baffle comprises a central hole.

17. A sound moderator as claimed in claim 16, wherein at least one baffle further provides a non-central hole.

18. A sound moderator as claimed in any of claims 1 to 17, wherein the moderator is of a 0.22" calibre.

19. A sound moderator as hereinbefore described with reference to Figs 1 to 5.